The invention relates to an ink pen assembly of a continuous ink jet printer.
As described in Jochimsen, U.S. Pat. No. 4,639,736, titled INK JET RECORDER, incorporated by reference herein, continuous ink jet printers produce a continuous stream of ink drops directed at a substrate. The ink drops include printing and non-printing drops. The ink drops are selectively charged such that the non-printing drops are deflected to prevent the non-printing drops from reaching the substrate.
A removable nozzle unit including a charging tunnel for producing a continuous stream of ink drops and charging the non-printing drops is described in Fargo et al., U.S. Pat. No. 5,160,938, titled METHOD AND MEANS FOR CALIBRATING AN INK JET PRINTER, incorporated by reference herein.